Phase-stable Cs-doped MAPbI₃ hybrid perovskite investigated through DFT-assisted structural, spectroscopic, EQE, and nonlinear optical analysis

Organic-inorganic hybrid perovskites are ideal materials for photodetection owing to their high charge carrier mobility, long charge carrier diffusion length, low dark current density and sharp absorption edge. However, a relatively small band gap (1.6 eV) limits their photon-harvesting efficiency in the near-infrared region. In the present work, we demonstrate a hybrid methylamine iodide and Pb-Sn binary perovskite as the light absorption layer in photodetectors. Experimentally, the wavelength of photoresponse onset for the photodetectors can be extended to as great as 1,000 nm when the Sn content of the hybrid perovskite is increased to 30 mol%. In addition, the photodetectors exhibit a photoresponsivity of 0.39 A W−1, a specific detectivity of 7×1012 Jones, a fast photoresponse with rise and decay time constants and an external quantum efficiency greater than 50% in the wavelength range of 350–900 nm, with a maximum value of about 80% at 550 nm.

In this work, we performed a computational screening of group IV transition-metal dihalide monolayers in the recently proposed 1T″ phase. We have thoroughly examined their structural, electronic, optical, and excitonic characteristics, using density functional theory with both the generalized gradient approximation (PBE) and hybrid (HSE06) exchange-correlation approaches including spin-orbit coupling, complemented by Wannier-function-based tight-binding and Bethe-Salpeter equation analyses; as well as phonon dispersion calculations and ab initio molecular dynamics to shed light on the material stability. Out of the nine candidate systems, only 1T″ ZrCl2, HfCl2, and HfBr2 were found to be dynamically and thermally stable, with semiconducting behavior observed exclusively for HfCl2. From a detailed analysis of this compound, we have revealed pronounced excitonic effects, with a binding energy of 275 meV, strong optical anisotropy, and broadband absorption covering the infrared, visible, and ultraviolet ranges. Moreover, efficiencies of up to 20% were obtained by evaluating the 1T″-HfCl2 photovoltaic performance using the spectroscopic limited maximum efficiency and the Shockley-Queisser limit. These results highlight 1T″-HfCl2 as a promising two-dimensional semiconductor for optoelectronic and solar energy applications.

Exploring flexibility, intermolecular interactions and ADMET profiles of anti-influenza agent isorhapontigenin: A quantum chemical and molecular docking study

Highly efficient luminescence material covering near‐infrared (NIR) I (700–1000 nm) and II (1000–1700 nm) is of great importance for phosphor‐converted NIR light‐emitting diodes (pc‐LEDs) light sources. The lack of ultra‐wide emission NIR luminescent materials that can be excited by cheap blue‐LEDs, suspends the applications of NIR pc‐LEDs. Ni2+‐activated phosphor usually gives an NIR‐II region emission, however, it presents low quantum efficiency due to poor absorption in blue light region. Here, a blue‐LED‐excitable (400–480 nm) LaMgGa11O19(LMG):Cr3+,Ni2+ NIR‐emitting phosphor is reported. Significantly, by constructing energy transfer from Cr3+ to Ni2+, it demonstrates an ultra‐wide NIR emission from 650 to 1600 nm, and greatly improves external quantum efficiency (EQE) from 2% to 53%. Besides, the weakened exchange coupling of Ni2+−Ni2+ pairs leads to an abnormal blue‐shift of Ni2+ emission with increasing temperature. The fabricated NIR pc‐LED gives a high output power of 8 mW at 20 mA with the photoelectric efficiency of 14%, which favors potential applications in night‐vision technology, medical applications, non‐destructive analysis, and spectroscopic analysis. This exploration of Cr3+‐Ni2+ co‐doped strategy for realizing high‐performance NIR‐emitting phosphor provides novel and effective design insights into developing more ultra‐broadband NIR pc‐LEDs based on cheap blue LEDs.

Revolutionizing energy storage demands innovative strategies that transcend the conven­ti­onal boundaries of electrode design. Here, we unveil a powerful approach that harnesses the synergistic interplay between dielectric and conductive nanophases to unlock unprecedented charge storage performance in polymeric supercapacitors. By individually synthesizing copper oxide (CuO) and barium titanate (BaTiO3) nanoparticles and strategically embedding them into a polyaniline (PANI) matrix, we engineered two finely tuned ternary nano­composites: PCB5 (10 wt.% CuO, 5 wt.% BaTiO3) and PCB10 (5 wt.% CuO, 10 wt.% BaTiO3). Advanced structural and spectroscopic analyses (X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Ramanspectroscopy) confirmed the successful integration of the nanophases, while dielectric studies revealed distinct variations in dielectric constant and interfacial polarization behaviour depending on nanoparticle ratios. Among the composites, PCB5 showed the most balanced electrochemical performance, with a specific capacitance of 271.67 F g-¹, outperforming pristine PANI and its BaTiO3-rich counterpart. Electrochemical impedance spectroscopy further confirmed the low series and charge-transfer resistances of the PCB5 composite sample, reflecting its efficient ion/electron transport pathways. Furthermore, BET analysis showed an increased surface area (31.37 m² g-¹) compared to pristine PANI (24.08 m² g-¹), providing additional electroactive interfaces for charge accumulation. These findings establish, for the first time, a dielectric-conductive co-engineering paradigm in PANI nanocomposites, where carefully optimized filler ratios act as a dual-function booster of both dielectric constant and electrochemical kinetics. This extraordinary synergy paves the way for transformative next-generation high-energy, high-power supercapacitors with tunable multifunctionality.

Graphene platelets with a large scale have been synthesized by reduction of graphene oxide (GO) in aqueous solution of hydrazine hydrate under microwave irradiation (MWI). Microstructure of the graphene was characterized by X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and transmission electron microscopy (TEM) together with the selected area electron diffraction (SAED). The electrochemical properties were evaluated by the analysis of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in 1 M Na2SO4aqueous solution. The results show that the as-prepared materials consist of crumpled, few-layer (~ 3 nm) thick and electronically conductive graphitic sheets. The supercapacitors fabricated using this material possess a low equivalent series resistance (ESR) value ~ 1.6Ω and a high specific capacitance of 285 F ⋅ g-1. In addition, the graphene reduced under a diverse duration of MWI displays a different interlayer spacing, extent of reduction, level of graphitization and specific capacitances. The duration of MWI and the treatment methods strongly affect the microstructure of graphene, and then dominate its electrochemical properties.

Synthesis of low leakage current chemical vapour deposited (CVD) diamond films for particle detection

Vibrational spectral analysis of 2-(2,4,6-Trichlorophenyl) hydrazinecarbothioamide was carried out using FT-IR and FT-Raman spectroscopic techniques. The equilibrium geometry and vibrational wave numbers have been computed using density functional B3LYP method with 6-311++G(d,p) as basis set. HOMO–LUMO energy and the thermodynamic parameters are also evaluated. The thermodynamic functions (heat capacity, internal heat energy, Gibbs energy and entropy) from spectroscopic data by statistical methods were obtained for the range of temperature 100–1000 K.

We report on the direct growth of radially oriented multiwalled carbon nanotubes (ROMWCNTs) on stainless steel (AISI 304L) fine-mesh substrate using the chemical vapor deposition (CVD) method to get a stable scaffold for supercapacitors using redox-active materials (e.g., metallic oxides and conducting polymers). The scaffold was characterized by different ‘ex situ’ (e.g., scanning and transmission electron microscopy, Raman, X-ray photoelectron and energy dispersive spectroscopy, surface area, and porosity analyses) and ‘in situ’ (e.g., cyclic voltammetry, chronopotentiometry, and electrochemical impedance spectroscopy) techniques. We explore this data to identify the origin of capacitance observed. Morphology factor (ϕ) parameter revealed that only 16% of the energy stored in the electrical double-layer is confined in the inner surface regions of the scaffold. It was verified a substantial contribution of the reversible solid-state surface faradaic reactions (RSFRs) to the overall specific capacitance observed. The coin cell was characterized by low equivalent series resistance, fast RSFRs, and very high stability during the galvanostatic charge-discharge experiments. All these results encourage further developments using the ROMWCNTs:AISI fine-mesh composite as a promising scaffold for applications in supercapacitors devices using redox-active materials.

The compound 2-[2-(Butylamino-4-phenylaminothiazol)-5oyl] benzothiazole was characterized by IR spectral data. The geometry of the molecule was investigated and optimized with the help of B3LYP/6–311G density functional theory (DFT) method using Gaussian 09’ software package. The calculated geometries such as bond lengths, bond angle, dihedral angle atomic charges and intensities of Vibrational bonds of the titled compound were investigated. The IR spectra are obtained and assigned by vibrational analysis and found to be reliable compared with the experimental results. The calculated Homo and LUMO energy gaps also confirm that charge transfer occurs within the molecule.

Molecular structure, vibrational, HOMO-LUMO, MEP and NBO analysis of hafnium selenite

High-brightness operational stability is a major challenge for the commercialization of perovskite light-emitting diodes (PeLEDs). Using combined morphological and spectroscopic analyses, we determined that compositional heterogeneity at the buried interface significantly limits the device operational stability. To address this, a fluorinated small molecule salt is introduced into the hole transport layer to modulate the crystallization of the perovskite layer. The multifunctional interfacial modifier serves as a nucleation center to promote crystal growth and mitigate low-n phases, thereby creating a more robust buried interface. As a result, the PeLEDs achieve a high external quantum efficiency of 29.2% with a remarkably low driving voltage. More importantly, the devices exhibit a remarkable T90 operational lifetime of 726 min at 1000 cd m-2. This study demonstrates the critical role of the buried interface in phase modulation and stability enhancement, providing a viable strategy for developing stable and energy-efficient perovskite optoelectronic devices.

I-V and impedance characterization of a solution processed perovskite based heterojunction photodetector

Effect of starting Fe precursor (Fe2O3 and Fe3O4) on the multiferroic properties of BST (Ba0.96Sr0.04Ti0.91Fe0.09O3) ceramics has been investigated. Considerable changes in the ferroelectric and magnetic properties of these ceramics were observed. High crystallinity, tetragonal structure and phase purity of both the samples were confirmed using X-ray diffraction analysis. The field emission scanning electron microscopy analysis confirmed the uniform grain growth in both the samples with an average grain size of ≈0.40 μm. X-ray photoelectron spectroscopy analysis confirmed the presence of Fe2+ only and both Fe2+ and Fe3+ in Fe2O3- and Fe3O4-doped samples. The Fe3O4-doped BST samples displayed higher Pr and Mr values (2.32 μC/cm2and 0.012 emu/g) as compared to Fe2O3-doped BST samples. The M-E coupling response (≈10.56%) too was observed to be more pronounced in Fe3O4-doped BST samples. Our research work suggests that Fe3O4 doping in BST is better suited for multiferroic applications due to the presence of multivalent Fe ions.

Natural dye-sensitized solar cells ( n -DSSCs) offer a sustainable and low-cost alternative to conventional photovoltaics. Three natural dyes - Cota tinctoria ( CTT ), Punica granatum ( PG ), and Linaria grandiflora ( LG ) - are investigated as a new eco-friendly sensitizer, and their photovoltaic performance is systematically correlated with energetic parameters. Comprehensive FT-IR, UV–vis, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) analyses were employed to evaluate the relationships between electron injection driving force ( ΔG inj ), recombination resistance ( R rec ), and open-circuit voltage ( V OC ). Among the investigated natural dyes, the CTT -based device obtained the highest short-circuit current density ( J SC = 2.11 mA cm −2 ), open-circuit voltage ( V OC = 610 mV), and efficiency ( η = 0.91%). The correlation identified between ΔG inj , R rec , and V OC indicates that injection and recombination energies determine the efficiency of devices. These insights establish a mechanistic framework linking molecular energy alignment with photovoltaic behavior and guide the design of next-generation bio-derived sensitizers. Importantly, the study shows that superior ΔG inj facilitates stronger electron injection into TiO 2 , while higher R rec values suppress interfacial recombination, collectively governing V OC and overall efficiency. Overall, the results demonstrate that interplay between ΔG inj and R rec governs the photovoltaic behavior of natural dye-based DSSCs, establishing Cota tinctoria as a particularly promising bio-derived sensitizer for next-generation solar energy applications.